Interpretive Summary: Prior to this work there was no established industrial clarification method of sweet sorghum juice. The industrial clarification method was developed using a minimum of clarification aids and energy to increase profitability. Fermentable sugars (glucose, fructose, and sucrose) and juice turbidity were examined before and after clarification along with macro and micro nutrients that are required for fermentation organisms that can generate value-added products.

Technical Abstract:
In recent years, there has been a dramatic increase in interest of sweet sorghum (Sorghum bicolor L. Moench) for small, medium, and large-scale manufacture of renewable, biobased fuels and chemicals. New fermentation organisms hold tremendous potential for the production of biobased fuels, chemicals, and materials from industrial sugar feedstocks, in particular syrups. Clarification of sweet sorghum juice will be critical to the production of stable, intermediate syrup feedstocks for efficient transport, storage, and year-round supply. Juices extracted from physiologically mature sweet sorghum hybrids as well as immature cultivar Topper 76-6 (Topper), were clarified using heat, heat-milk of lime, and heat-milk of lime-polyanionic flocculant at various temperatures and target limed pHs, and compared to the clarification of sugarcane (Saccharum spp. hybrids) juice. There was no significant loss of fermentable sugars (sucrose+glucose+fructose) across clarification for any of the clarification methods examined. Preheating the sweet sorghum juice from 85 to 100 °C not only produced clarified juices of low turbidity, but also with excellent turbidity control. For the cultivars studied, a minimum limed juice pH of ~6.3 was optimum for the clarification of sweet sorghum juice preheated to ~85 °C with 5 ppm polyanionic flocculant addition with respect to clarified juice turbidity, protein, calcium, starch, and to a lesser extent phosphate levels. Clarified juice non-sugar values are also discussed along with possible effects on later processing into value-added products. There was a strong effect of cultivar on juice quality, clarification performance, and clarified juice quality, which warrants further research.